1. Pour boiling water into a blender. Add Jello powder. Cover and blend at low speed until Jello is completely dissolved. about 30 seconds.
2. Combine cold milk and ice cubes to make 1 1/4 cups. Add to Jello in blender and stir with a spoon until ice is partially melted, then blend at high speed for 30 seconds.
3. Spoon into individual serving dishes.
4. Chill until set, about 30 minutes.